In the future, navigation devices rather than studs could be attached to the tongue

A futuristic device which helps people find their way around through sensors on the tongue has been developed.

Its makers believe that as well as helping people move about in the dark or deep underwater, it could eventually be used to help blind people get about.

But the Royal National Institute for the Blind (RNIB) in the UK warned the device was a long way off being available on the market, and was unlikely to replace white sticks and guide dogs.

The device, developed by scientists at the University of Wisconsin, US, works via a "tongue display unit".

Gold electrodes

The researchers, whose device is featured in New Scientist, identified an electronic resistance present in the tongue.

It is better than dry skin for conducting electrical impulses because it is constantly covered in conductive saliva, whereas skin is covered in dead skin cells and can go from sweaty to dry very quickly.

The tongue device is a stamp-sized grid of 144 gold-plated electrodes. One form of the device has a video camera that sends electronic signals to the grid.

The user then feels a tingling sensation, for example on the left side of their tongue if they need to go left.

Successful trial

Volunteer Cheryl Schiltz, who tested the device, used the tongue unit to find her way around a computer maze. With her eyes closed, she was guided by the computer as to which way to go.

The device then delivered a tingling sensation to the relevant part of the tongue to tell her the right direction.

She said: "It was amazing. Just by feeling it on my tongue, my brain got the message where to go."

She added that the device produces a "fizzy" sensation, not unlike sticking your tongue on a nine-volt battery. Developer Paul Bach-y-Rita said people were able to use the device after around 50 hours of practice.

Initial tests have used it to deliver very basic information. Within five years, it could be developed into a unit that fits into the mouth, or a wireless link from a video or sonar sensor mounted on a person's glasses.

The US Navy has already tested the device to help divers find their way through murky waters. Also possible is a system to help people who have lost their sense of balance.

'Extremely futuristic'

A device called an accelerometer could be attached to the head to sense if someone wobbles, and then correct them back left or right.

John Welsman, a spokesman for the RNIB, said the organisation had a very high regard for the team developing the device, but said it was extremely futuristic.

And he said even if there was money available to market and commercially produce the device, its cost would put it out of reach for the majority of people with sight problems.

There are two million people in the UK with sight problems. Of those of working age, 75% are going to be unemployed. Eighty per cent of people with sight problems are of retirement age or over.

Mr Welsman said most people would prefer to rely on traditional sight aids: "There's no mobility device that's ever replaced the guide dog and the white stick."

The RNIB helpline, which provides support information and advice to people with sight problems, can be contacted on 08457 669999